Tomato cultivation in Côte d'Ivoire is facing problems related to soil depletion. However, mineral fertilization of these soils remains expensive and almost inaccessible to many farmers in rural areas and contributes to environmental pollution. The aims of this work is to improve the growth and production of tomato by using the mycelium of Pleurotus ostreatus. Trials were carried out on plants from two tomato varieties F1 cobra 26 and Petomech. Four types of treatments were applied in this study; they are 10g of Pleurotus ostreatus mycelium; 5gof Pleurotus ostreatus mycelium; NPK and a control. The different treatments were done one week before transplanting and one week after transplanting. At the end of this work, all the treated plants had a significant effect on the different growth parameters studied compared to the control. The plants treated with 10g of Pleurotus ostreatus mycelium, one week before transplanting to Cobra 26, gave the best results of collar diameter, plant height and number of leaves. For the treatment one week after transplanting, only the plants treated with 10 g of Pleurotus ostreatus mycelium improved the diameter at the collar, the height of the stems and the number of leaves.